Rotary electric motor having concentric annular members

Abstract

A rotary electric motor in which rotor and stator members are each configured as annular rings, concentric with respect to each other, about an axis of rotation. Either of the rotor or stator members is formed of groups of electromagnet poles, the groups substantially equidistantly distributed along the angular extent of the annular ring, each of the groups comprising magnetic material magnetically isolated and separated from the other groups. The other member comprises a plurality of permanent magnet poles substantially equidistantly distributed with alternating magnetic polarity along the angular extent of the radial air gap formed between the members, the permanent magnet poles having a common magnetic return path.

1. A rotary electric motor comprising:
 a stator configured in the form of an annular ring having a plurality of groups of electromagnet poles, the groups substantially equidistantly distributed along the angular extent of the annular ring, each of the groups comprising magnetic material magnetically isolated and separated from the other groups, the electromagnet poles having pole faces separated from each other by gaps, gaps between pole faces within each group being of a substantially uniform first angular distance; and  
 an annular rotor, concentric with an axis of rotation and concentric with the annular stator to form a radial air gap therebetween, comprising a plurality of permanent magnets substantially equidistantly distributed with alternating magnetic polarity along the angular extent of the air gap and separated from each other by gaps of a second angular distance different from the first angular distance, the permanent magnets having a common magnetic return path;  
 wherein each group of electromagnet poles comprises windings that are switchably energized for driving electromotive interaction between the stator and rotor.  
 
   
   
     2. A rotary electric motor as recited in  claim 1 , wherein each stator group comprises no more than a single pair of poles, each pole having a winding configured to form a magnetic polarity opposite to the magnetic polarity of the other pole of the pair, wherein switched energization of the pole pair winding effects reversal of the magnetic polarities of the pole pair. 
   
   
     3. A rotary electric motor as recited in  claim 1 , further comprising a rotor position sensor, wherein signals for switching energization of the windings are generated in response to the sensor. 
   
   
     4. A rotary electric motor as recited in  claim 3 , wherein said position sensor comprises a resolver;
 and said motor further comprises an encoder for generating said signals.  
 
   
   
     5. A rotary electric motor as recited in  claim 1 , wherein the angular distance of the gaps between adjacent pole faces of each stator group differs from the angular distance of the gaps between adjacent stator pole faces of adjacent groups. 
   
   
     6. A rotary electric motor as recited in  claim 5 , wherein the angular distance of the gaps between adjacent poles of adjacent stator groups is different from the angular distance of the gaps between adjacent permanent magnets of the rotor. 
   
   
     7. A rotary electric motor as recited in  claim 1 , wherein the rotor surrounds the stator. 
   
   
     8. A rotary electric motor as recited in  claim 1 , wherein the number of stator groups is an odd number and the number of poles within each stator group is an even number. 
   
   
     9. A rotary electric motor as recited in  claim 1 , wherein each stator group is individually secured to a non-magnetically permeable support structure, thereby facilitating independent removal and replacement of an individual stator group and a switched energization circuit component associated therewith. 
   
   
     10. A rotary electric motor as recited in  claim 9 , wherein said support structure comprises:
 a plate member; and  
 a shaft member located at the axis of rotation;  
 wherein each of said stator groups is secured to said plate member at a spaced radial distance from the axis of rotation; and  
 said plate member is attached to said shaft member.  
 
   
   
     11. A rotary electric motor as recited in  claim 10 , wherein said spaced radial distance is greater than the radial distance between inner and outer boundary diameters of the stator annular ring. 
   
   
     12. A rotary electric motor as recited in  claim 9 , wherein said motor further comprises a rotor housing, the rotor annular rotor being mounted within the housing at a spaced radial distance from the axis of rotation, and the rotor housing is journalled for rotation about the shaft through bearings.